Field Scripting Help

Looking for an example script that will be deployed at the field level. The script should replace substrings. An example is the following:

ABBYY recognizes the order field on the form, right now it is recognizing the string to be S0l22334 when it should be recognizing SO122334. There are a few more cases where it is recognizing letters as numbers (and vice versa) as well. Really need some help with this one, thanks in advance!

Okay, so lets say I need the first two characters to always be recognized as letters (small or capital) and the rest of the characters to always be recognized as digits. Do you have an example of what that regular expression would look like? Everything I have tried so far stops my documents from being recognized at all.

Thank you for your help with this, this is our first project using ABBYY, and we are sooo close.

I took some tutorials on regex and have gotten to a point where everything is recognized as it should be, ie. order #s that were recognized as starting S0l are now recognized as starting SO1. The issue that I am facing now is that even though the regex is working, the document is still being sent to verification station due to a lack of confidence that the Os are really Os, even though the regex is telling ABBYY they are indeed Os. The regex I used for the field is: [A-Za-z][A-Za-z][0-9]{1-}